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Friday, 4 November 2016

The Search for Willow Emerald Damselfly Eggs

Unlike most damselfly species that lay their eggs beneath the surface of the water, the Willow Emerald Damselfly is quite unique in this country in that it lays its eggs in the thinner branches of a number of trees, Willow being a particular favorite as it often overhangs the water. The eggs which are laid in pairs either side of the insertion mark overwinter in the branch and begin to hatch from early April where they drop into the water and grow at an alarming rate. They also have an amazing mechanism in that if they fall on to dry land, they can spring on the surface until hopefully they reach the water. Having photographed most aspects of the Willow Emerald Damselfly this year, there was one part that I had not found and photographed, this being the egg stage. A look through the internet for any similar shots of Willow Emerald Damselfly eggs proved negative and I suspect that there have not been many, if any taken at all of this stage. With this in mind, I decided to visit Nethergong in east Kent to see if I could find a likely branch that I could use to discover the eggs. With a good population here, I soon found a number of willow trees and with the leaves now dying off, the characteristic scarring left by the female Willow Emerald Damselfly creating a ladder style effect was soon found on a number of thin branches.

Willow Emerald Damselfly 'Gall' Marks

It was pleasing whilst searching to find a good number of branches that had been used for egg laying, some being old ones but a lot I suspect were newer ones on the young branches. I carefully removed one branch of about 20cm in length and decided to bring it home to see if I could remove the bark to reveal the eggs inside. As I had never done this before, I was really quite unsure how to go about this but after coming up with a plan, I set to work. I decided to score a line with the scissors just under where the eggs had been inserted and carefully started to peel back the top layer of bark. With the aid of my Opticron 10x field lens, I was able to see some of the eggs still present and after studying them and finding a few more, I set about trying to capture this rare opportunity on camera.

Willow Emerald Damselfly Eggs Beneath the Bark

The eggs were barely visible to the eye and after positioning the branch so it was supported, I spent some time with the macro lens capturing a number of photos of the eggs. It was certainly another learning curve and an education to study and photograph this and amazing to think that they will spend the winter in the branches, hatch and grow next spring and emerge to be a stunning damselfly in the space of a few months. I will spend a number of sessions looking and monitoring throughout the winter the amount of egg laying I can find on the branches and with some found already in new areas this year, I hope next year is another successful one for this stunning damselfly.

Superb results Marc. I guess they are much less likely to be predated in this situation and with such a quick growth once hatched explains why they are spreading so rapidly. Have you looked for eggs in the nettles where you saw egg laying earlier?

Many thanks Bob. I have thought of doing this to confirm my observations. The only problem is that they are the other side of the stream. If I can find a plank to go over, then I really should take a look. If not take the mile round walk to the other side.

Many thanks Richard. Nice to add some detail photographically as there doesn't seem to be any other photos on the Internet. Hopefully one more visit this year to see them if the weather and time allow.